Apparatus for depalletizing articles and stacking empty pallets

ABSTRACT

Two depalletizing stations, preferably sharing a common empty pallet stacking station and a common inlet conveyor to be rendered operable by the automatic sequential feeding of loaded pallets to the inlets thereof from the common inlet conveyor. Alternatively, one of the depalletizing stations can be shut down when desired. When the depalletizing stations are both operated, article position and/or apparatus condition sensing means and associated control means responsive thereto control the movement of palletized articles from the common inlet conveyor to the conveyors extending from the common inlet conveyor to the depalletizing stations so palletized articles are automatically fed to a depalletizing station free to receive a new loaded pallet. The depalletizing stations most advantageously discharge articles upon respective article-receiving conveyors each of which is capable of discharging articles at either one of the same two discharge points when operating separately. Empty pallets from the depalletizing stations are fed to different sides of a common pallet stacking station which can receive pallets only one at a time from the depalletizing stations.

United States Patent [191 Burt et al.

Primary Examiner-Robert J. Spar APPARATUS FOR DEPALLETIZING ARTICLES ANDSTACKING EMPTY Att0rneySidney Wallenstein et a]. PALLETS ABSTRACT Twodepalletizing stations, preferably sharing a com- [75] Inventors: HaroldS. Burt, Mendota; Vasco O.

Carvalho, Skokie, both of I11.

Morton mon empty pallet stacking station and a common inlet conveyor tobe rendered operable by the automatic sequential feeding of loadedpallets to the inlets [73] Assignee: Conveyor Systems, Inc.,

Grove, Ill.

[22] Filed: Aug. 13, 1971 thereof from the common inlet conveyor.Alternatively, one of the depalletizing stations can be shut Appl. No.:171,554

down when desired. When the depalletlzmg stations are bothoperated,article position and/0r apparatus [52] US. 214/8 .5 A, 198/81, 214/6 H,

condition sensing means and associated control means responsive theretocontrol the movement of palletized 2l4/8.5 F, 8.5 G, 16 B, 6 P, 6 H;198/81; 53/61 [51] Int.

articles from the common inlet conveyor to the con- Field Of veyorsextending from the common inlet conveyor to the depalletizing stationsso palletized articles are antomatically fed to a depalletizing stationfree to re- [56] .Refel'ences Cited ceive a new loaded pallet. Thedepalletizing stations UNITED STATES PATENTS most advantageouslydischarge articles uponrespec- 214/16 B tive article-receiving conveyorseach of which is capable of discharging articles at either one of thesame two discharge points when operating separately.

214/8.5 A Empty pallets from the depalletizing stations are fed to Adifferent sides of a common pallet stacking station 214/16 B which canreceive pallets only one at a time from the 214/85 R x depalletizingstations.

2,470,922 5/1949' 2,866,564 12/1958 Kuper 2,944,702 7/1960Fenton............

3,107,794 10/1963 Bechtold et 3,113,683 12/1963 Von Gal, Jr. 3,173,5573/1965 Eliassen...........

3,181,712 5/1965 Von Gal, Jr. 3,263,827 8/1966Verrinder............................

6 Claims, 13 Drawing 3.776.396 SHEET 18F 9 PATENIEDUEC 4197a /WENTORSHAR LD 5, BURT VAsca 0. CnevnLHo PATENTEDBEB 41m SHEET 3 BF 9 0200mmlohm Quit.

[NVENTORS HAROLD S BURT VASCO O, Cn/evALHo ATTKS.

PATENTEUUZB '4 sum 5 OF 9 Nw um R ww nu E E 3% 3 ma 3 Q Q mm 1N vex/r025HAROLD 5. BURT Vnsco 0. CARVALHO F j Arm J PATENT BEB 4131 5 SHEET 8 OF9 JNVENTORS HAROLD 5. BURT flax;

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PATENTEDUEC M975 3.776.396

SHEET 8 OF 9 P16. 95 WW (REI'Too) 135' D INVENTORS HAROLD 5.51/21 V sco0. Cmvnwo @JWW, 9L A'rrvs.

' 1 APPARATUS FOR DEPALLETIZING ARTICLES AND STACKING EMPTY PALLETS' IThis invention relates to article handling equipment, and has its mostimportant application in equipment for handling depalletized articles,such as filled boxes stacked in tiers upon pallets which are deliveredto a depalletizing station where the tiers of boxes are removed one tierat a time from the pallets by automatic equipment which discharges thetiers of boxes upon an article-receiving conveyor. The depalletizingstation may include a support which can be elevated in steps to bringthe different tiers of boxes supportedon a pallet to the inlet stationof the article-receiving conveyor. After all the tiers of boxes areremoved from a pallet, the empty pallet is carried -to a pallet stackingstation where the pallet is dropped upon. a stack of empty pallets. Whena full load of empty pallets are received by the pallet stackingstation,-the pallet stack is moved to a remote discharge point. Duringthe time empty pallets are being stacked and a fullload of stacked emptypallets are being carried to a remote discharge point, the depalletizingstation cannot readily be depalletizing boxes, which reduces the rate atwhich the boxes from a given supply point can be depalletized by theequipment.

In accordance with one of the features of the present invention,'thehandling capacity of a depalletizing in-.

stallation can be greatly increased-with a minimum of additionalequipment'by integrating the control of at least two depalletizingstations sharing a common inlet conveyor. Article position and apparatuscondition sensing elements are provided to which apparatus control meansare responsive by feeding a loadedpallet from the common inlet conveyorto the depalletizing station which is ready to receive boxes to bedepalletized. The timing of the operation of the two depalletizedstations can be such that as one depalletizing station is operable todepalletize boxes thereat the equipment associated with the otherdepalletizing station can be discharging an empty pallet to a palletstacking sta-' tion and then receiving a new group of'palletizedarticles. It is most desirable that the two depalletizing stations sharea common pallet stacking station preferably positioned immediatelytherebetween and adapted to receive empty pallets fed to different sidesof the inlet end thereof. Control means may be provided to prevent thesimultaneous feeding of two empty pallets to the inlet end of thestacking station where the two depalletizing stations can besimultaneously completing a depalletizing operation at the same time.

Another feature of the invention is the provision of stacking apparatuswhich is designed tode'liver a full load of stacked empty pallets toa'remote discharge point without requiring a temporary shutdown in theoperation of stacking the pallets. To this end, temporary pallet holdingmeans are automatically brought I into position so as to hold newly fedempty pallets at the inlet of the stacking station until the main palletsupport apparatus returns from the remote discharge point, whereupon thetemporary pallet holding means automatically drops its load upon themain pallet support apparatus and then moves out of the path of travelof the pallets.

Still another important feature of the invention deals with a uniquearrangement of article-receiving conveyors receiving the articles sweptfrom the depalletizing stations, and related bypass apparatus whichpermits articles delivered to either one of the article-receivingconveyors to be-discharged to either one of the same twodischargepoints. This aspect of the invention is particularly usefulwhen the depalletizing system has an alternative mode of operationwherein either one of the aforesaid depalletizing stations canberendered operative while the other depalletizing station remainsinoperative because of the need of repairs of because the full operativecapacity of the system is not needed.

The above and other advantages and features of the invention will becomeapparent upon making reference to the specification to follow, theclaims and the draw ings wherein:

FIG. 1 is a perspective view of a preferred box conveyor anddepalletizingsystem in which palletized articles are delivered from acommon inlet conveyor to either one of two depalletizing stations and'inwhich depalletized articles are carried to either one of two'possibledischarge points at the inlet of a pair of outfeeding conveyors;

FIG. 1A is a view of an exemplary control panel for and depalletizingsystem of FIG. 1 includingthe common inlet conveyor and-a pair oftransversely extending infeeding conveyors which deliver articlesrespectively to the inlet sides of the depalletizing stations;

FIG. 3 is an end elevational view of the box conveyor and depalletizingsystem of FIG. 2, taken along viewing plan 3-3; I

FIG. 4 is a vertical sectional view through a portion of the boxconveyor anddepalletizing system of FIG. 1, taken along section line 4-4therein, and showing the manner in which the equipment depalletizesarticles and discharges empty pallets to a common pallet stackingstation;

FIG. 5 is a plan view of the box conveyor and depalletizing system ofFIG. 1;

FIG. 6 is a perspective view of the common pallet stacking station usedin the boxconveyor and depalletizing system of FIG. 1, with the mainpalletsupport apparatus shown in solid lines in a normal position toreceive pallets, and in dashed lines in a pallet discharging position; I

FIG. 7 is a simplified vertical fragmentary view of a portion of thestacking apparatus shown in FIG. 6, when the main pallet supportapparatus is moved out of position and a temporary pallet holding meansis brought into position temporarily to support new pallets fed to thepallet stacking station;

FIG. 8 is a vertical sectional view through the box conveyor anddepalletizing system of FIG. 8, taken along section line 8-8 in FIG. 5;and

FIG. 9A, 9B, 9C and 9D are logic circuit diagrams of the control meansresponsive to the various sensing element conditions tocontrol thevarious motors, solenoids and the like shown in FIGS. 1-8.

Referring now more particularly to FIG. 1, the exemplary form of theinvention there shown is a conveyor and depalletizing system for pallets2 carrying a load 4 of articles, such as packed boxes, arranged in tiers4a, 4b, 4c, etc., one on top of the other. As illustrated, each tier ofboxes comprises three longitudinally spaced pairs of boxes 4-1 and 4-2.Each load of boxes on a pallet 2 is delivered ona common inlet conveyor6 only adjacent the inlet end of a transversely extending infeedingconveyor 10 and an extension conveyor section 6 forming a continuationof the terminating common inlet conveyor section 6 and which may alsocomprise longitudinally spaced rollers 8 driven by a suitable drivemeans, such as chain and sprocket drive means 9 driven by a drive motor11. The end of the terminating common inlet conveyor section.6 is shownterminating at the inlet of a transversely extending infeeding conveyor10 to be described.

In the preferred form of the invention, the infeeding conveyors l andrespectively have frames (not shown) carrying pairs of rear sprockets16-16 and l6'-l6 respectively driven by drive motors 18-18 and pairs offront sprockets 19-19 and 19'19 around which sprockets extend pairs ofchains 12-12 and 12'-12'. The rear sprockets 16-16 and 16-l6 arerespectively located adjacent to the inlet ends of depalletizingstations 26-26. The front ends of the chains 12-12 and 1212 respectivelyare positioned to pass between or on one side of the rollers 8-8 of theadjacent inlet conveyor sections 6-6 and are normally below the tops ofthe rollers 8-8 as shown in solid lines in FIG. The front sprockets19-19 and 19'-19 are shown supported on the ends of a pair of pivotablymounted lever arms like 20 in FIG. 3, which are connected to the controlrods of hydraulic cylinders like 22 controlled by valves like 22aoperated by solenoids like 51 which when energized fill one end of theassociated cylinders with fluid to raise the front sprockets 19-19 andwhen de-energized cause the fluid to flow therefrom to drop thesprockets 19-19. The raising of the front sprockets bring the inlet endsof the chains 12-12 and 1212 slightly above the level of the roller 8-8of the associated common inlet conveyor sections, to raise any palletsupported on the latter rollers from the inlet conveyor sectioninvolved.

The upper sections of the raised chains 12-12 and 12'-12' respectivelycarry the pallets and their loads to the inlet ends of depalletizingstations 26 and 26.

The operation of the drive motors 11 and 11 drivingv the inlet conveyorsections 6 and 6' and the drive motors 18 and18' and solenoids S1 and S1controlling the infeeding conveyors 10 and 10' as well as other portionsof the box conveyor and depalletizing system are controlled by computerand/or manually operated controls in turn feeding signals to logiccontrol circuits like that shown in FIGS. 9A, 9B, 9C and 9D. FIG. 1Ashows a control panel 21 for manually controlling the box conveyor anddepalletizing system by means of system on-off push button controls 23aand-23b, depalletizing station select on-off controls 25-25 andoutfeeding conveyor select on-off controls 27-27. Push button control23a is depressed when it is desired to effect operation of the boxconveyor and depalletizing system and the push button control 23b isdepressed when it is desired to stop operation of the box conveyor anddepalletizing system. The depalletizing station select control 25 or 25'is moved to its on position when depalletizing stations 26 or 26 and itsassociated infeed-,

ing conveyor 10 or 10' are to be operated by the movement of palletizedboxes into a position opposite the same in a manner to be described. Ifboth depalletizing station select controls 25 and 25 are operated totheir on positions, then both infeeding conveyors 10 and I0 and thedepalletizing stations 26 and 26 are operated when palletized boxes aremoved into position opposite the same in a manner to be described. Whenonly depalletizing station 26 is operating, the drive motor 11 drivinginlet conveyor section 6 is rendered inoperative.

In the most preferred form of the invention,. the movement of therollers 8 and 8 of the conveyor sections 6 and 6', the movement of thechains 12-12 and 1212 of the infeeding conveyors l0 and 10, and theraising and lowering of the front ends of the chains 12-12 and 12'.12are under control of various article position sensing elements to bedescribed. When both depalletizing stations 26 and 26' are to beoperative, the conveyor sections 6 and 6 are under control of a logiccontrol circuit like that shown in FIGS. 9A

and 9B which will stop the conveyor sections 6 and 6' when bothdepalletizing stations 26 and 26 are in the process of depalletizing orstacking pallets and pallets are in position at the ends thereof. Also,in such case, the'system is designed to deliver a load of palletizedboxesfirst to the infeeding conveyor 10. To avoid interference betweensuccessive body in the absence of other load position sensing controls,it will be assumed that successive loads are spaced apart a distancegreater than the spacing between the infeeding conveyor'lO and 10. Tothis end, conveyor section stopping light sources 12-12 and associatedphotocell units 82-82 are placed on opposite sides of the ends of theconveyor sections.66 so the beams B2-B2' are intercepted by pallet loadsthereat. Also, conveyor section slow down limit switches LS-l and LS-l(FIG. 2) having sensing arms extending up between rollers 8 and 8 ofconveyor section 6' and 6 at points in advance of the light source L2-L2to sense the presence of pallet loads approaching positions opposite theassociated infeeding conveyors 10' and 10, respectively. In theexemplary form of the invention being described, the depalletizingstation 26 is the first station permitted to receive a pallet load, andso, if the depalletizing station 26 opposite the infeeding conveyor 10is available to receive a pallet load, the photocell unit B2 and limitswitch LS-l' opposite infeeding conveyorlO will be non-responsive to theincoming pallet load so the load can pass on to the end of conveyorsection 6. The next pallet load will, however, be effective in stoppingthe conveyor section 6. As the first pallet load operates limit switchLS-l, the motor 11 driving the inlet conveyor section 6 slows'down to afraction of its normal speed (like l0 feet per minute instead of 30 feetper minute) and the motor 1 1 stops when the light beam B2 of lightsource L2 is intercepted. When depalletizing station 26 is operating andif depalletizing station 26 is free to receive a new pallet load,operation of limit switch LS-l will operate the motor 11 driving inletconveyor section 6 at a reduced speed and the interception of beam B2 oflight source L2 will stop the motor 11'.

As the slower moving pallet load involved reaches its final positioncentered above the inlet end of the lowered infeeding conveyor 10 or10'involved, the interception of light beam B2 or B2 which stops motor11 or 1 l will also effect the energization of the previously mentionedsolenoid S1 or S1 controlling the raising of the inlet end of theinfeeding conveyor or 10'. The chains 12-12 or l2'-l2 of the infeedingconveyors 10 or 10' involved will then lift the pallet load off of theinlet conveyor section 6 or 6'. When the chains 12-12 10 feet per minutespeed referred to previously, and to de-energize the solenoid Slvor S1which riased the front end of the infeeding conveyor, thereby loweringthe same. When the pallet load is slightly in advance of itsrearwardmost position on the infeeding conveyor 10 or 10', the palletload is located within the lower inlet end of the depalletizing station26 or 26' and it trips a limit switch LS-4 or LS-4' which effects thestoppage of the infeeding conveyor'drive motor l8 or18 at a pointslightly there beyond because of a slight coasting of the infeedingconveyor.

It should now be apparent that with a conveyor and depalletizing systemoperating as just described, the common inlet conveyor sections willautomatically supply, via the infeeding conveyors, pallet loads to adepalletizing station free to receive a new pallet load.

As perhaps is best shown in FIG. 4, the depalletizing stations 26-26preferably include pallet support platforms 28-28. The chains 12-12 andl2' -l2' of the infeeding conveyors 10-10" respectively extend onopposite sides of the associated pallet support platforms 28-28.Initially, the pallet support platforms 28-28 are positioned at anelevation below the infeeding conveyor chains 12-12 and 12l2' wherelimit switches LS-S and LS-S' are depressed to indicate that theassociated depalletizing stations 26 and 26" are free to receive apalletload. When pallet loads are respectively delivered to the rearends of infeeding con- In the upward movement of each pallet supportplatform 28 or 28", the platform is-moved successively into threepositions where the bottom planes of the differentbox tiers 4a, 4b and4c are positioned in the plane of an associated article-receivingconveyor 34 or 34. In these respective positions, the platforms 28-28"respectively operate limit switches LS-8, LS-lO, LS-ll and LS-8', LS-lOand LS-11' which operate when pushed upward by a rising pallet tode-energize the solenoid 34a or 34a which stops the platforms 28 or 28.

In the most preferred form of the invention, each of thearticle-receiving conveyors 34 or 34 are roller conveyors driven bychain' and sprocket drive mchanisms 36 or 36', in turn, driven bysuitable drive motors 38 or Each tier of boxes as illustrated isremovedfrom the associated pallet support platforms 28-28, or thetien of boxestherebelow, by suitable box discharging apparatus 40-40. FIG. 3 bestillustrates the box discharging apparatus 40 of depalletizing station26, it being understood that box discharging apparatus 40' associatedwith depalletizing station 26' is identical to apparatus 40 andcorresponding parts thereof are similarly numbered except for theaddition of a prime thereto.

Box discharging apparatus 40.is an endless chain conole-receivingconveyor. In a manner to be described, as

veyor 10-10 above the support platforms 28-28,

the pallet loads trip limit switches LS-4a and LS-4a' to effect raisingof the platforms 28-28 to pick the pallet loads off of the associatedinfeedingconveyors 10-10 to raise the sametowardthe elevated dischargeends of the depalletizing stations 26-26. The pallet support platforms28-28 are shown respectively connected to fluid is fed into theassociated hydraulic cylinder 35 or 35 to cause the associated palletsupport platform 28 or 28' to move upwardly. When the solenoid 31b or31b is energized, hydraulic fluid is fed to the associated cylinder 35or 35- to effect the downward movement of the associated pallet supportplatform 28 or 28'.

soon as a tier of boxes is pushed upon the associated article-receivingconveyor 34, then the operative pusher plate 42 engages a limit switchLS-9 which de-energizes the associated conveyor drive motor 43 until thetier of boxes involved are cleared at least from the portion of thearticle-receiving conveyor 34 opposite the discharge end of the conveyor40.

Referring now more particularly to FIGS. 1 and 5, the discharge end ofthe conveyor (which is the discharge end of the depalletizing station26) is'positioned intermediate the'opposite ends of thearticle-receiving conveyor 34. The-pusher plates 42-42 of the conveyor40 move the articles onto the article-receiving conveyor 34 over idlerrollers 41 in a direction parallel to the axes of rotation of therollers 47 thereof. One end of the article-receiving conveyor 34 ispositioned adjacent'one side of the inlet end of an outfeeding conveyor45' extending transversely away from the articlereceiving conveyor 34and the opposite end of the article-receiving conveyor 34 is positionedadjacent one side of the inlet end of an outfeedi'ng conveyor 45. Out

feeding conveyors 45-45 are preferably roller conveyors with rollers46-46 extending transversely of the rollers 47-47 of articlereceivingconveyors 34-34, When the depalletizing station 26 is operated or whenonly depalletizing station 26' is operating and prferably continuouslyoperated at a relatively slow speed and is operable selectively torotate the rollers 47 in one direction or the other depending on whetherdelivery of boxes to outfeeding conveyor 45 or 45' is called for. Whenboth of the depalletizing stations 26-26 are operative in the embodimentof the invention shown in the drawing, the article-receiving conveyor 34is driven in a direction where the boxes delivered thereto are fed tothe inlet end of the out-feeding conveyor 45. A relatively high speedseparator roller 54 positioned between the end of the article-receivingconveyor 34 adjacent the outfeeding conveyor 45 is driven by a motor 52at a higher speed then the speed of the rollers 47 of thearticle-receiving conveyor 34 so that the successive pairs of boxesconstituting one of the tiers of boxes just fed upon the conveyor 34will be separated. A high speed separator roller 54 positioned at theend of the article-receiving conveyor 34 adjacent the outfeedingconveyor 45 is driven by a motor 52" at a higher speed then the speed ofthe rollers 47 of the article-receiving conveyor 34 so that thesuccessive pairs of boxes constituting one of the tiers of boxes justfed upon the conveyor 34 will be separated when moved upon theoutfeeding .conveyor 45. The outfeeding conveyors 45 and 45 operate at amuch faster speed than the article-receiving conveyors 34 and 34 so thatthe outfeeding conveyors move each pair of boxes out of the way beforethe next pair of boxes reach the separator roller involved. An abutmentwall 55 positioned between the article-receiving conveyor 34 and, theinlet end of the outfeeding conveyor 45' is mounted for up and downmovement by a solenoid 59 (FIG. 8) between a bottom position where it isbelow the level of the outfeeding conveyor 45 and a raised positionabove the level thereof where the boxes delivered upon the inlet end ofthe outfeeding conveyor 45 from the article-receiving conveyor 34 willnot overshoot the outfeeding conveyor 45'.

The discharge end of the box removing conveyor 40' (which is thedischarge end of the depalletizing station 26') is positioned oppositethe article-receiving conveyor 34' so as to deliver articles thereuponover the idler'rollers 41 in a direction parallel to the axes ofrotation of the rollers 47 of the article-receiving conveyor 34'. Whenthe depalletizing station is operating, the rollers 47 are driven bymotor 38 in a direction to move articles at a relatively slow speedtoward the opposite side of the inlet end of the outfeeding conveyor 45from the side located adjacent to the articlereceiving conveyor 34. Anabutment wall 55' positioned between the separator roller 54" at thelatter end of the article-receiving conveyor 34 and the inlet end of theoutfeeding conveyor 45' is mounted for up and down movement by asolenoid 59' (FIG. 8) between a bottom position where it is'below thelevel of the outfeeding conveyor 45 and a raised position above thelevel thereof, as shown in FIG. 1, where the boxes delivered upon theinlet end of the outfeeding conveyor 45' from the article-receivingconveyor 34' will not overshoot the outfeeding conveyor 45'. A boxseparator roller 54' positioned between the articlereceiving conveyor34' and the inlet end of the outfeeding conveyor 45' is driven by amotor 52' which moves the separator roller 54' at a higher speed thenthe rollers of the article-receiving conveyor 34' to separate theadjacent pairs of boxes of a tier of boxes fed upon thearticle-receiving conveyor 34.

When both depalletizing stations'26-26' are in operation, as aboveindicated, the article-receiving conveyor 34-34 respectively feeds boxesto the inlet ends of the outfeeding conveyors 45-45', and, in such case,the abutment wall 55 is in a raised position and the abutment wall 55 isin a lowered position, as shown in FIG. 1. An abutment wall 55" ispositioned on the outside of the inlet end of the outfeeding conveyor 45to prevent overshooting of boxes fed upon the end of the outfeedingconveyor 45 by the article-receiving conveyor 34.

As previously indicated, in the mode of operation of the conveyor anddepalletizing system where only one of the depalletizing stations 26 or26' is in operation, the article-receiving conveyor 34 can be operatedin one direction or the other by operation of the outfeeding conveyorcontrols 27 or 27 on the control panel 21 shown in FIG. 1A. When onlythe depalletizing station 26 is to be operated and it is desired todischarge articles upon the outfeeding conveyor 45, operation of theoutfeeding conveyor 27 to its ON position will effect automatically thelowering of abutment walls 55 and 55 and the raising of driven skaterollers 61 (see FIGS. 5 and 8) by solenoid 62 from a position where theskate rollers located between the rollers 46' of outfeeding conveyor 45are completely below the level .of the rollers- 47 46 and 47 of theconveyors 34, 45 and 34, to a position slightly above the same (see FIG.8), where the skate rollers carry boxes from the inlet end of thearticle-receiving conveyor 34 to the end of the article-receivingconveyor 34 adjacent the outfeeding conveyor 45, thereby-bypassing theoutfeeding conveyor 45. The article-receiving conveyor 34 will thendeliver the articles to the inlet end of the outfeeding conveyor 45.

As previously indicated, the pusher plates 4242 or 42'42 associated withthe box discharging conveyors or 40' instrumental in sweeping tiers ofboxes off of the associated pallet support platform 28 or 28 areautomatically stopped as a tier of boxes is delivered upon thearticle-receiving conveyor 34 or 34, and resumes operation only when theboxes are cleared from the article-receiving conveyor 34 or 34'involved. Article position sensing means are provided to sense thepresense or absence of boxes in position on the articlereceivingconveyor34 or 34'. Although these sensing means may take a variety offorms, as illustrated in FIG. 5, when the article-receiving conveyor 34operates in a direction to deliver articles to the outfeeding conveyor45, a light source L3 is provided directing beam B3 diagonally acrossthe article-receiving conveyor 34 toward the outfeeding conveyor 45. (Inthe alternative, a reflector may be positioned where the photocell unitPC-3 is located and a photocell unit may be suitably positioned toreceive a reflected beam). As long as the light beam B3 is interruptedby a box on the articlereceiving conveyor 34 or the inlet end of theoutfeeding conveyor 34, the photocell unit PC-3 effects a controloperation to terminate movement of the associated box dischargingconveyor 40. When, the article-receiving conveyor 34 is operated in adirection to move the articles to the inlet end of the outfeedingconveyor the light source L3 is de-energized and another light source L4is energized to direct a light beam B4 diagonally across thearticle-receiving conveyor 34 toward the outfeeding conveyor 45' towarda photocell unit PC-4 (or reflecting surface) mounted on the then raisedabutment wall 55.. (The photocell unit is thus only moved into positionto receive the light beam B4 when the abutment wall is raised into anarticle box stopping position.) It can thus be seen that when all boxeshave been removed from the article-receiving conveyor 34 and the inletend of the outfeeding conveyor 45 or 45, the box discharging conveyor 40associated with the outlet end of the depalletizing station 26 resumesmovement to sweep another tier of boxes upon the article-receivingconveyor 34.

Similarly, when depalletizing. station 26' is in operation, pusherplates 42 of the box discharging conveyor 40' are inhibited frommovement as long as boxes remain on the article-receiving conveyor 34.To this end, light source L3, under the circumstances when thearticle-receiving conveyor 34' is operative to move articles to theoutfeeding-conveyors 45', directs light beam B3 and B4 across thearticle-receiving conveyor 34' toward photocell unit PC-3 on the thenraised abutment wall 55. The light beams B3 is interrupted when a tierof boxes is first moved upon the article-receiving conveyor 34 whichinterruption remains until the last of these boxes is moved off of theinlet end of the outfeeding conveyor 45'; t

- As best shown in FIG. 4, after all of the tiers of boxes have beenremoved from a pallet 2 supported on a pallet support platform 28 or 28,the platform involved is lowered to anintermediate point where thepallet is opposite the inlet end of a pallet stacking station 67 locatedimmediately between and shared by the two depalletizing stations 26-26.The control circuit for reversing the direction of the platforms maytaker-a variety of forms. An exemplary logic circuit diagram for such acontrol circuit will be'later described and is shown in FIGS. 9A and 9B.The pallet stacking station 67 receives pallets from the opposite sidesof the inlet end thereof delivered thereto from the pallet supportplatforms 28-28. An empty pallet delivered to the inlet end of thepallet stacking station 67 is pushed from the pallet support platforms28 or 28' by pusher member 70 or'70' shown secured to the end of anoperating rod of a hydraulic cylinder 72 or 72- operated by controlvalve 74 or 74. The control valves 74-74 include solenoids 76a-76awhich, when energized, effect the extension of the associated pushermembers -70" respectively to push the pallet involved to continuouslydriven pallet feeding rollers 78-78, and

when de-energized, effect the retraction of the associated pushermembers 70-70.

The pallet stacking apparatus includes adjacent each of thedepalletizing stations 26-26 pairs of laterallyspaced columns 80-80and'80-80 between which are mounted for up and down movement, as byrollers 82-82, pallet support -members 84-84. As best shown in FIG. 6,the elevation of the pallet support 1 members 84-84 are controlled byhydraulically operated pulley assemblies 86-86. The pulley assemblies86-86 respectively include a pair of cables 88-90 and 88-90' having oneof their ends suitably anchored to stationary points 92- 92. Cables88-90 and 88' pass around suitable pulleys94-94 carried by brackets96-96 secured to the operating rods 98-98 of hydraulic cylinders100-100. Cables 88-90 and 88-90' pass around'the bottom of the gagementwith the associated pallet stacking member As the operating rods 98-98of the cylinders 100-100 rise from their positions shown in FIG. 6, thepal-let stacking members 84-84' are lowered on the columns 80-80 and80'-80". The cylinders 100-100 are respectively controlled by solenoidcontrolled valve control apparatus 110. The valve 110 has a solenoid 112which, when energized, result in the retraction of the operating rods98-98, and. a solenoid 114 which, when energized, effect the upwardextension of the operating rods 98-98.

Normally, the pallet support members 84-84' are at an elevationsubstantially contiguous to but spaced below the point at which palletsare moved into the pallet stacking station by the rollers 78-78.

The movement of a pallet into the pallet stacking station from palletsupport platform 28 will momentarily break the beam B5 of a light sourceL5 directedtoa photocell unit PC-S, and the movement of a pallet intothe pallet stacking station from pallet support platform 28' willmoementarily break the beam- B5 of a light source L5 directed to aphotocell unit PC-S'. When the pallet drops fully into the palletstacking station, its previously interrupted beam is re-established andthis de-energiz'es the associated pusher member operating solenoid whichretracts the pushermember involved.

The simultaneous feeding of two pallets into the stacking station isprevented by an interlock control of any kind, such aslimit switchesL12a-L12a' which are operated when the respective pusher members 70-70leave their fully retracted positions. The limit switches Ll2a-L12a arerespectively in the control circuits of 'the respective solenoids76a-76a', so each pusher member cannot be extended unless the otherpusher member is fully retracted.

A pallet is guided by guide plates 79-79 into position where it drops arelatively short distance upon the pal- 40 let support members 84-84'.When approximately six pallets have been stacked upon the pallet supportmembers 84-84 suitable control apparatus are operated, such as a delayoperating photocell unit PC-6 (FIG. 5) mounted to receive a lightbeam B6of a light source L6. The momentary interruption of the light beam B6will have no effect, buta prolonged interruption caused by the sixth andsubsequent pallets will effect e'nergization of solenoid 114.as long asthe beam is interrupted -105' where they extend downwardly to make entocause the lowering of the pallet stacking members 84-84 a distance equalto the thickness of one pallet,

to permit a clearance space for another pallet to be fed onto the stackof pallets at the pallet stacking station.

When a full load of pallets have been stacked upon the pallet stackingmembers 84-84, control apparatus, such as limit switch LS-17 (FIG. 4),is operated by the downward movement of the bottommost pallet in thestack to effect the high speed movement of the pallet support members toa bottommost position where the pallets are delivered upon apalletdischarge conveyor 117 (FIG. 6) operated by a drive motor 117. Duringthe initial high speed downward movement of the pallets, a limit switchLS-l9 (FIG. 4) or the like is operated. When the pallet support membershave lowered the stack of pallets upon the conveyor 11.7, a light beamdirected to a photocell unit PC-7 .is interrupted, a limit switch LS-20(FIG. 6) is operated which deenergizes solenoid 114 to stop the downwardmovement of the pallet support members, operate drive motor 117 for aperiod to deliver the pallets to a remote point when the light beamdirected to photocell unit PC-7 is reestablished to effect the reverseor upward movement of the pallet support members by energization of thesolenoid 112. During the initial high speed downward movement of thepallet support members which operated limit switch LS-19, temporarypallet holding means are brought into position to receive temporarilyother pallets delivered to the pallet stacking station. The temporarypallet holding means, as shown in FIGS. 6 and 7, may comprise a pair ofshoulder-' forming members 119-119' pivotably mounted for movement bycontrol solenoids 120-120 energized by operation of a limit switch LS-19by the'bottom pallet in the stack. The shoulder-forming members 119-119are mounted for movement between normal inoperative positions where theyare out of the path of travel of pallets moved into the pallet stackingstation to opervoltage pulse of a given polarity, such as positive, isnecessary to effect a stepping operation. Also, all the limit switcheswill be assumed to be normally open switches which are closed whenoperated for the variative positions where they form support shouldersfor i supporting pallets delivered to the pallet stacking station, asbest shown by the solid line positions of these temporary pallet holdingmeans in FIG. 7. As soon as the pallet support members 84-84 arereturned to their normal initial elevation, control means like limitswitch LS-22 is operated to effect de-energization of solenoids 120-l20' to move temporary pallet holding means 119-119 out of the way ofincoming pallets and deenergization of solenoid 112 to stop the upwardmovement of the pallet support members.

FIGS. 9A, 9B, 9C and 9D are exemplary logic circuit diagrams ofexemplary means for controlling the various motors and solenoids inresponse to the operation of the various switches and photocell unitspreviously described. It should be understood that numerous otherarrangements of switches, photocell units and logic circuit elementscould be provided to accomplish the unique mode of operation of theinvention described and claimed without deviating from the broaderaspects of the invention.

The exemplary logic circuits of FIGS. 9A and 98 respectively control thefeeding of palletized articles to, and the operation of, thedepallatizing stations 26 and 26 by means like stepping switches orshift registers (stepping switches 130-130' being illustrated) by themovement of the palletized articles past the various switches andphotocell units previously described. (Thus, while stepping switches areillustrated, it is understood that shift registers or the like could besubstituted for the stepping switches shown in the exemplary form of theinvention being described.) Each vof the stepping switches 130 and 130'as shown include 15 active stationary contacts numbered 0 through 14which are rendered sequentially operative to energize various controlelements which may be solenoids and/or relays connected to or associatedwith the various stepping switch contacts. The advancement of thestepping switches is controlled by the feeding of pulses or voltagecharges to stepping means 132 and 132'. The stepping switches havemovable contacts like 131 or 131' which successively make contact withthe No. 0 through No. 14 contacts undercontrol of the voltage charges orpulses fed to the stepping means 132 or 132'. Stepping means 132 and 132receive pulses or voltages which effect a stepping operationrespectively from common input lines 133 and 133' or the outputs of ANDgates 136 and 136'. It will will be assumed that a change to a constantvoltage of a given polarity or a 136' has an input from an circuit 134'.The outputs of the AND gates 136 and 136' are respectively conouscircumstances previously described to provide a positive voltage output.Similarly, it will be assumed that the various photocell units produce apositive voltage output only when the light beam directed thereto isinterrupted. The various OR circuits and AND gates indicated throughoutthe logic circuit diagram operate in accordance with well-knownprinciples for these types of logic circuit elements. That is, for anAND gate all inputs must have the proper operating polarity (positive inthe exemplary form of the invention) to produce an operating outputvoltage which is further assumed to be of the exemplary positivepolarity. Also, OR circuits produce a positive operating output onlywhen any one of its inputsis a positive voltage. Inverter circuitsidentified by INV will be assumed to product a positive output only whenits input is non-positive. Moreover, the outputs from the various limitswitches and photocell units are shown identified by reference numeralsl-14 and 0 to indicate that positive voltag'e outputs thereof are torespectively effect operation of the associated stopping switch movablecontact 131 or 131 to the correspondingly numbered stationary contactsof the stepping switch involved.

The common input lines 133 and 133' are repsectively connected tocontrol elements PC-2, PC-2', LS-2, LS-2', LS-3 LS-3, LS-4, LS-4, LS-4a,LS-4a, LS-8, LS-8, LS-9, LS-9, LS-10, LS-10', LS-ll, LS- l1, LS-12,LS-12, PC-S, PC-S', LS-12a, LS-l2a and LS-S and LS-S'. The inputs of theAND gates 136 and 136 are the select switches 25 and 25, limit switchesLS-l and LS-l and the output of the No. 1 contacts of the steppingswitches and 130'. The AND gate nected to inputs of the stepping means132 and 132'. When the movable contact 131 of stepping switch 130 is onthe No. 0 contact, the stepping switch 130 cannot step unless a palletreaches limit switch LS-l, and depalletizing station select switch 25 isin its ON position. (Manually operable means not shown may be providedto move contacts 131 and 131 many initial desired contact position.) Toadvance the movable contact 131' of stepping switch 130 from the No. 0contact position, in addition to the ON or operated state of selectswitch 25 and limit switch LS-l a signal from OR gate 134' must be fedto AND gate 136 which occurs only when depalletizing station 26 isrendered inoperative by the OFF state of select switch 25 or whendepalletizing station 26 is in operation as indicated by the movablestepping switch contact 131' being on a contact other than the No. 0contact of stepping switch 130'. To thisend, the select switch 25 andthe No. 0 contact of stepping switch 130 are connected to inverters and137' whose outputs are connected to the OR circuit 134'.

FIGS. 9A and 98 (as well as FIGS. 9C and 9D) show boxes or other circuitelements connected with the various stationary stepping switch contacts.The boxes are identified in accordance with the particular functions tobe carried out by the components represented thereby. Thus, for example,the various boxes may be relays or the like with contacts performing thefunctions indicated .thereon and so the box 139 in FIG. 9A

connected to the No. stepping switch contact of stepping switch 130 andentitled Initiate Fast Operation of which effects the function involvedeven when the movable contact like 131 leaves the associated contactuntil a stop operation is called for. Thus, the box 139 may be a relaywhich locks into an energized state through a holding circuit (notshown) containing holding contacts of the relay or a relay with contactsenerigizing another relay which locks in through its own contacts toenergize the control circuit of motor 11 to operate the same at arelatively fast speed.

The box 141 associated with the No. 1 stepping switch contact ofstepping switch 130 and entitled Initiate Slow Operation of Motor-l1similarly represent a relay having contacts which effects the locked-inenergization itself of another relay whose contacts effect thecontinuous feed of a voltage to the input of the con trol circuit ofmotor 11 which operates the motor at a relatively slow speed and breaksthe holding circuit of the locked-in relay which previously energizedthe input of the motor control circuit which operated the motor at ahigh speed. There is shown connected to the No. 2 stepping switchcontact control components 143 and 145 respectively as carrying out thefunctions of initiating the locked-in fast operation of motor 11 and 1initiating the locked-in energization of infeeding conveyor raisingsolenoid S1 in a manner like that just described.

When the word Initiate is absent in describing the function of a. givencomponent, this means that the component involved is energized onlyduring the time the particular stationary stepping switch contact isenergized and so no holding circuits are associated with the relays orthe like to be energized. Thus, for examnent 149 may be a relay withnormally closed contactsin the holding circuit of a relay which effectsthe slow operation of motor 18 and was previously'locked-in an energizedstate when the No. 3 contact of the stepping switch was energized by theengagement thereof by the movable contact 131. Thus, energization of theNo. 5 stepping switch contact would, in the exemplary relay circuit,result in the opening of the normally closed relay contacts referred toin the holding circuit of the locked-in relay to de-energize the sameuntil the same is subsequently energized by a subsequent closure of arelay contact effect by another operation of the stepping switch. OtherStop functions indicated in the logic circuit diagram may be effected inthis manner.

Since it'is obvious to anyone skilled in the artof electrical controlcircuit design to design a particular relay circuit to carry out thefunctions indicated in the logic circuit diagrams of FIGS. 9A, 9B, 9Cand 9D, such specific circuit diagrams have been omitted to avoidcluttering this specification with unnecessary details.

The manner in which the remainder of the circuits associated with thestepping switches 130 and 130 are self-evident from the drawings in thelight of the explanation of the meaning of the symbols and expressionsabove described.

The logic circuit'diagrams of FIGS. 9A and 9B include, in addition tothe stepping switch circuits introduced above, logic circuit sections150 and 150 which effect the stopping of the motors 11 and 11controlling the inlet conveyor sections during various previouslydescribed circumstances other than the one effected by the movement ofthe movable stepping switch contacts to the-No. 2 stationary contacts;For example, a logic circuit section 150 is provided (FIG. 9A) which iseffective in stopping the motor 11 controlling the extension inletconveyor section 6 when at a given movement an article reaches the firstlimit switch LS-l and the select switch 25 is in its OFF position(i.e..when the depalletizing station 26 is to be inoperative) or when apalletized articleis in the process of being fed by the infeedingconveyor 10 to palletizing station 26 or the the limit switch LS-l' whena palletized article in in the 1 process of being fed by the infeedingconveyor 10' to palletizing station 26 or the depalletizing station 26'is in operation (as indicated by the movable contact 131 being on thestationary contacts other than No. 0 and No. 1 contacts of steppingswitch 130), and a positive output is present in the aforesaid ORcircuit 134 (which occurs when either depallatizing station 26 is busyor inoperative).. I

The aforesaid functions may be carried out by means including an ANDgate 152 in logic circuit section (FIG. 9A) which has one inputconnected to the limit switch contacts LS1'.1;0 receive apositivevoltage when the same is operated, and an input connected to the outputof an OR circuit 134.'The OR circuit 134 has one inputconnected'thr'ough an inverter 135 to the output of an OR circuit 157whose two inputs are respectively connected to the No. 0 and No. 1contacts of the steppingswitch 130, and an input connected through aninverter 137 to the select switch 25. The

output of AND gate 152 is connected to a control device which effectsthe stopping of the motor 1 l and thus may be a relay having contacts intheholding circuits of the fast and slow operating inputs to the controlFIG. 9C shows the logic circuit diagram which effects movement of thepallet support members 84-84 in the manner previously described. Thislogic circuit diagram includes a stepping switch 200 or the. like withonly five active stationary contacts No. 04 and stepping means 202 whichreceives stepping pulses from the various limit switches and photocellunits indicated.

FIG. 9D shows the logic circuit diagram which responds to the variouscontrol switches on the panel 21 shown in FIG. 1A which operates themotors 38 and 38 forward or backward controlling the articlereceivingconveyors 34 and 34' and the solenoids 59, 59' and 62 which effect theraising and lowering of the abutment walls 55 and 55' and skate wheels61.

It is thus apparent that the present invention has eflected a highlyefficient and flexible integration of conveyors, depalletizing stationsand a common pallet stacking station which represents a substantialimprovement in the art of handling and depalletizing palletizedarticles.

It should be understood that numerous-modifications may be made in thepresent form of the invention without deviating from the broader aspectsof the same.

We claim:

l. A conveyor and depalletizing system comprising first and seconddepalletizingstations each incuding a loaded pallet-receiving inlet, acommon inlet conveyor for carrying pallets loaded with articles from acommon inlet point to the vicinity of said second depalletizing station,said common inlet conveyor'having a terminating conveyor section withcontrollable drive means for rendering the same operable and inoperable,conveyor means extending from the end of said terminating conveyorsection to the inlet of said first depalletizing station and havingcontrollable drive means for rendering the same operable and inoperable,conveyor means extending from the end ofsaid terminating conveyorsection to the inlet of said second depalletizing station, palletposition sensing means associated with the terminating conveyor sectionof the common inlet conveyor, and depalletizing station conditionresponsive means associated with said depalletizing station forindicating whether the associated depalletizing station is ready toreceive a loaded pallet at the input thereof for depalletizing andpallet stacking. first select means having on and off conditions forrespectively conditioning for operation and rendering inoperable thefirst depalletizing station, second depalletizing station select meanshaving on and off conditions for respectively conditioning for operationand rendering inoperable the second depalletizing station, and controlmeans responsive to said first and second depalletizing station selectmeans and to said depalletizing station condition sensing means andpallet position sensing means for operating said conveyor means to feeda loaded pallet on the terminating conveyor section to the input ofeither one of said depalletizing stations ready to receive the samewhere said first and second select means are operated to said onposition, and for rendering the conveyor means extending from the end ofsaid terminating conveyor section to said first depalletizing stationinoperable to feed loaded pallets thereto when said first depalletizingstation select means is in its ofi position and for rendering saidconveyor means extending from the terminating end of said terminatingconveyor section to said second depalletizing station inlet inoperablewhen said second depalletizing station select means is in its offcondition.

2. The conveyor and depalletizing system of claim 1 wherein each of saiddepalletizing stations has an article discharge point, first and secondarticle-receiving conveyors respectively adjacent each of the articledischarge points of said first and second depalletizing stations, thearticle-receiving conveyor associated with said first depalletizingstation selectively operable in one direction or the other to dischargearticles at one or the other of two possible discharge points, thearticle-receiving conveyor associated with said second depalletizingstation operable to discharge articles to one of said discharge pointsdirectly or to the other discharge point via the other article-receivingconveyor, and there is provided discharge point select means forselecting either one or both of said discharge points to which articleson said article-receiving conveyor can be fed, and said control meansincluding means responsive to said discharge point select means and tosaid depalletizing station select means for' operating said firstarticle-receiving conveyor to carry articles to the selected dischargepoint when only the first depalletizing station is operable, and foroperating said second article-receiving conveyor to discharge articlesto said one discharge point is selected and to said first article- Ireceiving conveyor operating in a direction to deliver articles to theother discharge point when the other discharge point is selected andonly said second depalletizing station is operable;

3. The conveyor and depalletizing system of claim 2 wherein said controlmeans include means independently of the conditions of said dischargepoint selectmeans for operating said first outfeeding conveyor todischarge articles to said other discharge point and for operating saidsecond article-receiving conveyor to discharge articles to aid onedischarge point when the depalletizing station select means are both intheir ON conditions.

4. A conveyor and depalletizing system comprising first and seconddepalletizing stations each including a pallet support means movablebetween a loaded palletreceiving inlet to article and pallet dischargingpoints and controllable drive for moving the pallet support meansbetween said points, a common inlet conveyor for carrying pallets loadedwith articles from a common inlet point to the vicinity of said seconddepalletizing station, said common inlet conveyor having a terminatingconveyor section, an extension conveyor section extending from the endof said terminating conveyor section of said common inlet conveyor tothe vicinity ing controllable drive means, said infeeding conveyorshaving means movable from a lowered position where they are respectivelybelow the ends of said conveyor sections and a raised position wherethey raise palletized articles on said conveyor sections therefrom tocarry the same to the inlets of the associated depalletizing stations,pallet position sensing means located at the ends of said conveyorsections for sensing the position of palletized articles above thelowered ends of said infeeding conveyors, said terminating conveyorsection of said common inlet conveyor and said exten' sion conveyorsection having drive means respectively for rendering the same operableand inoperable, depalletizing station condition responsive means forsensing the condition of operation of said support means of saiddepalletizing stations, and control means resonsive to saiddepalletizing station condition'sensing means t 17 for effecting thefeeding of a loaded pallet via the extension conveyor if necessary andthe appropriate infeeding conveyor to the inlet of the depalletizingstations ready to receive a loaded pallet, said control means includingmeans responsive to the depalletizing station condition responsive meansindicating that pallet support means of said first depalletizing stationis in position to receive a loaded pallet for operating the drive meansof said terminating conveyor section and the drive means of saidextension conveyor section for conveying a loaded pallet from saidcommon inlet conveyor to a point opposite the inlet end of said firstinfeeding conveyor and for then effecting the raising of the inlet endof said first infeeding conveyor which then carries a loaded pallet tothe inlet of said first depalletizing station, said control meansincluding means responsive to a depalletizing station conditionresponsive means indicating that the pallet support means of said seconddepalletizing station is in position to receive a loaded pallet foroperating said drive means of said terminating conveyor section to saidinoperative statewhen the loaded pallet reaches the end of saidterminating'conveyor section and for then effecting the raising of theinlet end of said second infeeding conveyor which then carries a loadedpallet to the inlet of said second depalletizing station, and palletposition sensing means associated with said depalletizing stations foroperating said drive means of said pallet support means thereat when thepallets are there delivered to render said depalletizing stationsoperative to energize said drive means thereof to move said supportmeans to said article and pallet'discharge points and then return thesame to said inlet points.

5. A conveyor and depalletizing system comprising first and seconddepalletizing stations, a common inlet sensing means located at the endsof said conveyor sections for sensing the position of palletizedarticles thereat, s'aid terminating conveyor section of said commoninlet conveyor and said extension conveyor section having drive meansrespectively for rendering the same operable and inoperable, first andsecond dcpalletizing station condition responsive means for rcspectivelysensing whether or not said first and second depalletizing stations arein a condition to receive loaded pallets, and control means includingmeans re- 7 sponsive to said first depalletizing'station conditionreconveyor for carrying pallets loaded with articles from a common inletpoint to the vicinity of said second depalletizing station, said commoninlet conveyor having a terminating conveyor section, an extensionconveyor section extending from the end of said terminating conveyorsection of said common inlet conveyor to the vi-.

sponsive means indicating that pallet support means of said firstdepalletizing station is in position to receive a loaded pallet foropera'tiong the drive means of said terminating conveyor section and thedrive means of said extension conveyor section for conveying aloadedpallet from said common inlet conveyor to a point opposite the inlet endof said first infeeding conveyor which then carries a loaded pallet tothe inlet of said first depalletizing station, and said control means including means responsive to said second depalletizing station conditionresponsive means indicating that the second depalletizing station is ina condition to receive a loaded pallet for operating said drive means ofsaid terminating conveyor section to said inoperative state when theloaded pallet reaches the second infeeding conveyor at the end of saidterminating conveyor section which second conveyor section then carriesa loadedpallet to the inlet of said second depalletizing station.

6. The conveyor and depalletizing system of claim 5 wherein each of saidfirst and second depalletizing stations has a pallet support meansmovable between a loaded pallet-receiving inlet to article and palletdischarge points, and controllable drive means for moving the palletsupport means between said inlet and article and pallet dischargepoints, and there is provided pallet position sensing means associatedwith each of said depalletizing stations for operating the drive meansof the associated pallet support means thereat when the palmeans thereofto move the associated support means to said article and palletdischarge points and then return 7 the same to said inlet point.

1. A conveyor and depalletizing system comprising first and seconddepalletizing stations each inc uding a loaded palletreceiving inlet, acommon inlet conveyor for carrying pallets loaded with articles from acommon inlet point to the vicinity of said second depalletizing station,said common inlet conveyor having a terminating conveyor section withcontrollable drive means for rendering the same operable and inoperable,conveyor means extending from the end of said terminating conveyorsection to the inlet of said first depalletizing station and havingcontrollable drive means for rendering the same operable and inoperable,conveyor means extending from the end of said terminating conveyorsection to the inlet of said second depalletizing station, palletposition sensing means associated with the terminating conveyor sectionof the common inlet conveyor, and depalletizing station conditionresponsive means associated with said depalletizing station forindicating whether the associated depalletizing station is ready toreceive a loaded pallet at the input thereof for depalletizing andpallet stacking, first select means having on and off conditions forrespectively conditioning for operation and rendering inoperable thefirst depalletizing station, second depalletizing station select meanshaving on and off conditions for respectively conditioning for operationand rendering inoperable the second depalletizing station, and controlmeans responsive to said first and second depalletizing station selectmeans and to said depalletizing station condition sensing means andpallet poSition sensing means for operating said conveyor means to feeda loaded pallet on the terminating conveyor section to the input ofeither one of said depalletizing stations ready to receive the samewhere said first and second select means are operated to said onposition, and for rendering the conveyor means extending from the end ofsaid terminating conveyor section to said first depalletizing stationinoperable to feed loaded pallets thereto when said first depalletizingstation select means is in its off position and for rendering saidconveyor means extending from the terminating end of said terminatingconveyor section to said second depalletizing station inlet inoperablewhen said second depalletizing station select means is in its offcondition.
 2. The conveyor and depalletizing system of claim 1 whereineach of said depalletizing stations has an article discharge point,first and second article-receiving conveyors respectively adjacent eachof the article discharge points of said first and second depalletizingstations, the article-receiving conveyor associated with said firstdepalletizing station selectively operable in one direction or the otherto discharge articles at one or the other of two possible dischargepoints, the article-receiving conveyor associated with said seconddepalletizing station operable to discharge articles to one of saiddischarge points directly or to the other discharge point via the otherarticle-receiving conveyor, and there is provided discharge point selectmeans for selecting either one or both of said discharge points to whicharticles on said article-receiving conveyor can be fed, and said controlmeans including means responsive to said discharge point select meansand to said depalletizing station select means for operating said firstarticle-receiving conveyor to carry articles to the selected dischargepoint when only the first depalletizing station is operable, and foroperating said second article-receiving conveyor to discharge articlesto said one discharge point is selected and to said firstarticle-receiving conveyor operating in a direction to deliver articlesto the other discharge point when the other discharge point is selectedand only said second depalletizing station is operable.
 3. The conveyorand depalletizing system of claim 2 wherein said control means includemeans independently of the conditions of said discharge point selectmeans for operating said first outfeeding conveyor to discharge articlesto said other discharge point and for operating said secondarticle-receiving conveyor to discharge articles to aid one dischargepoint when the depalletizing station select means are both in their ONconditions.
 4. A conveyor and depalletizing system comprising first andsecond depalletizing stations each including a pallet support meansmovable between a loaded pallet-receiving inlet to article and palletdischarging points and controllable drive for moving the pallet supportmeans between said points, a common inlet conveyor for carrying palletsloaded with articles from a common inlet point to the vicinity of saidsecond depalletizing station, said common inlet conveyor having aterminating conveyor section, an extension conveyor section extendingfrom the end of said terminating conveyor section of said common inletconveyor to the vicinity of said first depalletizing station, first andsecond infeeding conveyors respectively extending from the ends of saidterminating and extension conveyor sections to the inlets of said firstand second depalletizing stations, said terminating and extensionconveyor sections having controllable drive means, said infeedingconveyors having means movable from a lowered position where they arerespectively below the ends of said conveyor sections and a raisedposition where they raise palletized articles on said conveyor sectionstherefrom to carry the same to the inlets of the associateddepalletizing stations, pallet position sensing means located at theends of said conveyor sections for sensing the position of palletizedarticles above the lowered ends of said infeeding conveyors, saidterminating conveyor section of said common inlet conveyor and saidextension conveyor section having drive means respectively for renderingthe same operable and inoperable, depalletizing station conditionresponsive means for sensing the condition of operation of said supportmeans of said depalletizing stations, and control means resonsive tosaid depalletizing station condition sensing means for effecting thefeeding of a loaded pallet via the extension conveyor if necessary andthe appropriate infeeding conveyor to the inlet of the depalletizingstations ready to receive a loaded pallet, said control means includingmeans responsive to the depalletizing station condition responsive meansindicating that pallet support means of said first depalletizing stationis in position to receive a loaded pallet for operating the drive meansof said terminating conveyor section and the drive means of saidextension conveyor section for conveying a loaded pallet from saidcommon inlet conveyor to a point opposite the inlet end of said firstinfeeding conveyor and for then effecting the raising of the inlet endof said first infeeding conveyor which then carries a loaded pallet tothe inlet of said first depalletizing station, said control meansincluding means responsive to a depalletizing station conditionresponsive means indicating that the pallet support means of said seconddepalletizing station is in position to receive a loaded pallet foroperating said drive means of said terminating conveyor section to saidinoperative state when the loaded pallet reaches the end of saidterminating conveyor section and for then effecting the raising of theinlet end of said second infeeding conveyor which then carries a loadedpallet to the inlet of said second depalletizing station, and palletposition sensing means associated with said depalletizing stations foroperating said drive means of said pallet support means thereat when thepallets are there delivered to render said depalletizing stationsoperative to energize said drive means thereof to move said supportmeans to said article and pallet discharge points and then return thesame to said inlet points.
 5. A conveyor and depalletizing systemcomprising first and second depalletizing stations, a common inletconveyor for carrying pallets loaded with articles from a common inletpoint to the vicinity of said second depalletizing station, said commoninlet conveyor having a terminating conveyor section, an extensionconveyor section extending from the end of said terminating conveyorsection of said common inlet conveyor to the vicinity of said firstdepalletizing station, first and second infeeding conveyors respectivelyextending from the ends of said terminating and extension conveyorsections to the inlets of said first and second depalletizing stations,said terminating and extension conveyor sections having controllabledrive means, pallet position sensing means located at the ends of saidconveyor sections for sensing the position of palletized articlesthereat, said terminating conveyor section of said common inlet conveyorand said extension conveyor section having drive means respectively forrendering the same operable and inoperable, first and seconddepalletizing station condition responsive means for respectivelysensing whether or not said first and second depalletizing stations arein a condition to receive loaded pallets, and control means includingmeans responsive to said first depalletizing station conditionresponsive means indicating that pallet support means of said firstdepalletizing station is in position to receive a loaded pallet foroperationg the drive means of said terminating conveyor section and thedrive means of said extension conveyor section for conveying a loadedpallet from said common inlet conveyor to a point opposite the inlet endof said first infeeding conVeyor which then carries a loaded pallet tothe inlet of said first depalletizing station, and said control meansincluding means responsive to said second depalletizing stationcondition responsive means indicating that the second depalletizingstation is in a condition to receive a loaded pallet for operating saiddrive means of said terminating conveyor section to said inoperativestate when the loaded pallet reaches the second infeeding conveyor atthe end of said terminating conveyor section which second conveyorsection then carries a loaded pallet to the inlet of said seconddepalletizing station.
 6. The conveyor and depalletizing system of claim5 wherein each of said first and second depalletizing stations has apallet support means movable between a loaded pallet-receiving inlet toarticle and pallet discharge points, and controllable drive means formoving the pallet support means between said inlet and article andpallet discharge points, and there is provided pallet position sensingmeans associated with each of said depalletizing stations for operatingthe drive means of the associated pallet support means thereat when thepallets are delivered thereto, to render the associated depalletizingstation operative to energize the drive means thereof to move theassociated support means to said article and pallet discharge points andthen return the same to said inlet point.